JuliaCon 2026

Plane-wave density-functional theory (DFT) is one of the most widely employed simulation approaches for modelling materials atomistically, taking an accurate quantum-mechanical description of electrons. Since 2019 we develop the Density-Functional ToolKit (DFTK, https://dftk.org), a Julia-based code for plane-wave DFT. Right now, with about 10k lines of code, the code remains tractable, despite we recently managed to considerably expand its features. Noteworthy recent extensions is the scaling to multiple GPUs as well as advanced and expensive electronic structure models, such as Hybrid DFT or DFT with Hubbard corrections. I will sketch the challenges with respect to keeping code concise despite the feature extension and why we believe this is the right direction in the age of differentiable scientific computing. Despite our goal to avoid hand-optimised code and custom kernels, our code has state-of-the-art performance, which I will illustrate with some recent benchmarks.

This talk reports on work that has been conducted over the past two years jointly with many DFTK contributors, including Augustin Bussy (ETH Zürich), Bruno Ploumhans (EPFL), Antoine Levitt (Université Paris-Saclay), Tobias Schäfer (TU Vienna), Niklas Schmitz (EPFL), Francesco Sicignano (Scuola Normale Superiore, Pisa).